Super-hydrophobic fluorine containing aerogels

• US 20030032681A1
• Filed: 09/21/2001
• Published: 02/13/2003
• Est. Priority Date: 05/18/2001
• Status: Abandoned Application

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Hrubesh, Lawrence W., Poco, John F., Coronado, Paul R.
• Application Number:
  US09/957,853
• Publication Number:
  US 20030032681A1
• Time in Patent Office: Days
• US Class Current: 516/98
• CPC Class Codes: B01J 13/0091 Preparation of aerogels, e.g. xerogels
• CPC Class Codes: C01B 33/159 Coating or hydrophobisation
• CPC Class Codes: C01P 2006/10 Solid density
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C08J 2205/026 Aerogel, i.e. a supercritically dried gel
• CPC Class Codes: C09C 1/3081 Treatment with organo-silicon compounds
• CPC Class Codes: Y10T 428/2995 Silane, siloxane or silicone coating

Abstract

An aerogel material with surfaces containing fluorine atoms which exhibits exceptional hydrophobicity, or the ability to repel liquid water. Hydrophobic aerogels are efficient absorbers of solvents from water. Solvents miscible with water are separated from it because the solvents are more volatile than water and they enter the porous aerogel as a vapor across the liquid water/solid interface. Solvents that are immisicble with water are separated from it by selectively wetting the aerogel. The hydrophobic property is achieved by formulating the aerogel using fluorine containing molecules either directly by addition in the sol-gel process, or by treating a standard dried aerogel using the vapor of fluorine containing molecules.

Claims

1. In an aerogel material, the improvement comprising:

providing the aerogel material with hydrophobic properties produced by the addition of fluorine to the surfaces of the material.

2. The improvement of claim 1, wherein the addition of the fluorine is carried out by one of the group consisting of the addition of fluorine during the sol-gel process, and by treating a dried aerogel with fluorine vapors.

3. The improvement of claim 1, wherein the addition of the fluorine is carried out by utilizing a fluorine containing compound having at least one carbon-metal bond per molecule.

4. The improvement of claim 1, wherein not greater than about 30% by weight of the fluorine containing compound is utilized.

5. The improvement of claim 4, wherein the fluorine containing compound is selected from the group consisting of perfluoralkyl-alkoxysilanes, perfluoro alkyl chloro-silanes and alkoxy-fluroro silanes and metal alkoxides.

6. The improvement of claim 5, wherein the fluorine containing compound is composed of trifluoropropyl-trimethoxysilane.

7. The improvement of claim 1, wherein the surfaces have a surface contact angle is in the range of 90°

and 180°

.

8. The improvement of claim 7, wherein the contact angle is greater than 135°

.

9. A hydrophobic aerogel material with surfaces containing fluorine atoms.

10. The aerogel material of claim 9, wherein the fluorine containing material is transparent.

11. The aerogel material of claim 9, wherein the fluorine containing material has a contact angle between 90°

and 180°

.

12. The aerogel material of claim 11, wherein the contact angle is greater than 135°

.

13. The aerogel material of claim 9, wherein the fluorine containing material is produced using fluorine containing compounds of less than 30% by weight of fluorine containing alkoxides.

14. A method for producing hydrophobic aerogels comprising one of the group consisting of adding fluorine containing molecules during the sol-gel process, and treating a dried aerogel using the vapor of fluorine containing molecules.

15. The method of claim 14, wherein the fluorine containing molecules are obtained from a compound having at least one carbon-metal bond per molecule.

16. The method of claim 14, wherein the fluuorine containing molecules are from compounds selected from the group consisting of perfluoralkyl-alkoxysilanes, perfluoro alkyl chloro-silanes and alkoxy-fluroro silanes and metal alkoxides.

17. The method of claim 15, wherein the compound is a fluoro-methyl containing alkoxide.

18. The method of claim 15, wherein the compound is 3,3,3-trifluoropropyl-trimethoxysilane with tetramethorysilane.

19. The method of claim 14, wherein the aerogels have a contact angels between 90°

and 180°

.

20. The method of claim 19, wherein the contact angles are greater than 135°

.